We investigated the laminar and turbulent impinging jet for drag reducing surfactant solutions. The counterion was added at the molecular ratio to surfactant of 1:1 or 10:1. Although both solutions showed turbulent drag reduction in pipe flow, different flow was observed in the impinging wall flow depending on the counterion concentration. The solution with equimolar counterions showed the rheological behavior such as a Bingham plastic in an impinging jet, and the radial wall flow was blocked at some radial location by surrounding quiescent solution and turned perpendicular to wall. The radius of this wall flow was increased with the Reynolds number. When the impinging wall flow was turbulent, the shear flow and turbulence appeared in the thin wall layer between impinging wall and quiescent solution. By contrast, the surfactant solution with excess counterions developed laminar and turbulent boundary layer flow on the impinging wall similarly as water. These flow characteristics were consistent with the past study, which showed that the surfactant solution with excess counterions maintained the similar heat transfer as water.
2013 The Society of Rheology, Japan